Add more Spec command test coverage

Change STDIN to $stdin so it can be reassigned
Use UI.puts instead of print
Add test coverage for Spec#choose_from_array
Fix off by one issue in Spec#choose_from_array

Closes #1675
[Rakefile] Print boostrap information on Travis
[Rakefile] Force build Xcodeproj native extensions on Travis
[travis] Qu'est-ce qui se passe?
[bundle] As we install xcodeproj from the repo, it should always build.
[bundle] Yay, whack-a-mole.
[bundle] Re-instate usage of bundle dir.
[travis] Don't install bundle groups we don't need for a test run.
[travis] Don't try to load debugging gems.
[bundle] Diffy is required by the integration tests.